1. Technical Field
The present invention generally relates to a passenger protection apparatus and, more particularly, to a passenger protection apparatus configured such that the sufficient tensile force of a seat belt is ensured in an initial inflation stage of an airbag folded like a belt and provided at the position of a shoulder belt when the airbag is inflated upon the detection of a vehicular collision to extend from the chest part to a shoulder part of the passenger, and that subsequent deformation of the airbag enables the passenger protection apparatus to effectively restrain the passenger.
2. Related Art
The assignee of the present application developed a passenger protection apparatus (hereinafter referred to as an airbelt apparatus) configured such that an airbag housed in a shoulder belt of a seat belt is inflated around a portion extending from the chest part to a shoulder upper part of a passenger and that a single manufactured airbelt apparatus can deal with two accident modes, i.e., a frontal collision and a lateral collision (see Takata Corporation, “Vehicular Safety System Maker Takata Corporation Exhibits Airbelt at Good Design Exposition (EXPO) 2011”, [online], Aug. 24, 2011 [retrieved on May 20, 2012], Internet, <http:www.takata.com/pdf/110824_JP.pdf>).
This airbelt apparatus is such that the airbag is inflated along the shoulder belt worn by the passenger so as to have a substantially spindle shape thereby to increase the contact area between the airbag and the chest part of the passenger and to disperse and alleviate impact to be imposed on the chest part.
However, this airbelt apparatus is provided with two retractors that respectively wind a lap-belt-side part of the seat belt with respect to a tongue fixed to the seat belt and a shoulder-belt-side part of the seat belt, which houses the airbag as an airbelt, with respect to the tongue. Consequently, cost is high. Thus, this airbelt apparatus is assumed to be mounted in a luxury car or the like.
On the other hand, the assignee advances the development of another airbelt apparatus configured such that a shoulder belt into which an airbelt is incorporated and a lap belt provided opposite to the shoulder belt with respect to a tongue plate can be drawn from and wound into a single retractor. However, in the case of using the single retractor, it is necessary to configure the airbelt apparatus such that when a piece of webbing is drawn out of the retractor, an airbelt part (i.e., a part of the shoulder belt) having a tongue provided with a tongue plate and a gas supply port at an end portion thereof can smoothly slide against the webbing to an appropriate position between the chest part and the shoulder part, in addition to the drawing of a predetermined amount of the lap belt.
JP-A-2001-260807 discloses an airbelt apparatus configured to solve the above problem and to enable that webbing is surely wound using only a single retractor. The airbelt apparatus disclosed in JP-A-2001-260807 is such that a bag assembly 7 formed substantially-flat accommodates, in a cover formed with warp-knitted knit-fabric, the webbing 4 and an airbag in which a gas passage 22a and four elongated gas chambers 22b are formed in parallel.